Blue Ca4MgAl2Si3O14:Ce3+, Li+ phosphor with excellent performance for human-centered green plant growth lighting

Abstract

Light-emitting diodes (LEDs) can regulate the light environment for plant growth to increase productivity. Deep blue light, which plays a pivotal role in plant photosynthesis, has received limited attention in research due to the challenges associated with synthesizing a blue phosphor exhibiting high thermal stability, high quantum efficiency and spectral similarity to plant response spectra. This study presents the synthesis and characterization of a blue phosphor Ca4MgAl2Si3O14:xCe3+,yLi+, which is characterized by remarkable thermal stability and quantum efficiency reached through charge compensation. The introduction of Li+ ions eliminates cation vacancy defects, mitigates charge imbalance due to heterovalent substitution, and acts as a flux, thereby effectively suppressing energy transfer between Ce3+ ions and significantly improving several key properties of the phosphor. Notably, the emission intensity is significantly enhanced, the internal quantum efficiency was increased from 74.2 to 91.6 %, and the external quantum efficiency was improved from 54.9 to 67.7 %. Moreover, the thermal stability at 423 K was augmented from 71 to 82 %. Of particular importance is the exceptional alignment of the phosphor's spectrum with the absorption spectrum of chlorophyll-a (with a spectral resemblance of SRchlorophyll-a = 94.39 %). These findings underscore the great potential of Ca4MgAl2Si3O14:xCe3+,yLi+ phosphors in applications related to plant growth lighting.